Subclinical cardiopulmonary dysfunction in stage 3 chronic kidney disease

Benefits of Cardiac Rehabilitation in Cardio-Renal Patients With Heart Failure With Reduced Ejection Fraction

PURPOSE

Chronic kidney disease (CKD) is common in heart failure (HF). Chronic kidney disease often worsens the prognosis and impairs the management of patients with HF. Chronic kidney disease is frequently accompanied by sarcopenia, which limits the benefits of cardiac rehabilitation (CR). The aim of this study was to evaluate the impact of CR on cardiorespiratory fitness in HF patients with reduced ejection fraction (HFrEF) according to the CKD stage.

METHODS

We conducted a retrospective study including 567 consecutive patients with HFrEF, who underwent a 4-wk CR program, and who were evaluated by cardiorespiratory exercise test before and after the program. Patients were stratified according to their estimated glomerular filtration rate (eGFR). We performed multivariate analysis looking for factors associated with an improvement of 10% in peak oxygen uptake (V˙ o2peak ).

RESULTS

Thirty-eight percent of patients had eGFR <60 mL/min/1.73m². With decreasing eGFR, we observed deterioration in V˙ o2peak , first ventilatory threshold (VT1) and workload and an increase in brain natriuretic peptide levels at baseline. After CR, there was an improvement in V˙ O2peak (15.3 vs 17.8 mL/kg/min, P < .001), VT1 (10.5 vs 12.4 mL/kg/min, P < .001), workload (77 vs 94 W, P < .001), and brain natriuretic peptide (688 vs 488 pg/mL, P < .001). These improvements were statistically significant for all stages of CKD. In a multivariate analysis predicting factors associated with V˙ o2peak improvement, renal function did not interfere with results.

CONCLUSIONS

Cardiac rehabilitation is beneficial in patients with HFrEF with CKD regardless of CKD stage. The presence of CKD should not prevent the prescription of CR in patients with HFrEF.

Cardiopulmonary exercise testing to observe subclinical abnormalities in cardiopulmonary function in patients undergoing peritoneal dialysis

BACKGROUND

Decreased cardiorespiratory fitness (CRF) related to cardiopulmonary function increases the risk of cardiovascular disease in patients with end-stage kidney disease. Thus, early detection of the cause of impaired cardiopulmonary function in patients undergoing peritoneal dialysis (PD) is of important clinical significance.

METHODS

In this cross-sectional study, Symptom-restricted cardiopulmonary exercise testing (CPET) was performed in 30 patients undergoing PD and in 23 age- and sex-matched healthy control subjects.A fixed workload was added every minute until fatigue, and breath-by-breath respiratory gas was analyzed with an automated gas analyzer at 10-second intervals.

RESULTS

The peak oxygen uptake ( 16.39±0.83 vs 25.77±1.33 ml/kg/min p<0.001) and the oxygen uptake at the anerobic threshold of patients undergoing PD (9.61±0.34 vs 14.55± 0.64 ml/kg/min; p<0.001) were lower than in healthy control subjects, and both of these parameters correlated with body mass index and left atrial dimension. A steeper minute ventilation / carbon dioxide production slope (27.20±0.68 vs 24.29±0.69；p<0.01) and a lower end-tidal carbon dioxide partial pressure (37.93±0.54 vs 41.27±0.83mmHg；p<0.05) were observed in patients undergoing PD. The oxygen pulse and oxygen uptake efficiency slope was smaller in patients undergoing PD. The Maximum heart rate (126.07±4.01 vs 149.96±5.29 bpm；p<0.01) and 1-minute heart rate recovery (13.93±1.52 vs 24.39±1.61bpm；p<0.01) were also lower in patients undergoing PD.

CONCLUSION

Subclinical cardiopulmonary dysfunction may exist in patients with PD, and a reduction in CRF in patients undergoing PD is affected by both central and peripheral functions. CPET has potential value in revealing the mechanism of impaired CRF and in discovering subclinical abnormalities in cardiopulmonary function. This article is protected by copyright. All rights reserved.

Cardiopulmonary reserve examined with cardiopulmonary exercise testing in individuals with chronic kidney disease: A systematic review and meta-analysis

BACKGROUND

Patients with chronic kidney disease (CKD) often present reduced physical activity and exercise tolerance due to factors relevant to co-existing disturbances of the cardiac, nervous and muscular systems. Cardiopulmonary exercise testing (CPET) is used for clinical evaluation of exercise limitation and related symptoms (i.e., dyspnea, fatigue) in several medical fields.

OBJECTIVES

This is a systematic review and meta-analysis of studies using CPET technology to examine cardiopulmonary reserve in individuals with versus without CKD.

METHODS

Literature search involved PubMed, Web of Science and Scopus databases; manual search of article references and of gray literature was also performed. Observational studies and randomized trials that used CPET for patients with CKD stage 1-5 versus controls were eligible. The primary outcome was peak oxygen uptake (VO₂peak). The Newcastle-Ottawa Scale was used to evaluate the quality of retrieved studies.

RESULTS

From an initial 4944 literature records, we identified 29 studies fulfilling the inclusion criteria; of these, 25 studies (2,213 participants) with complete data were included in the final meta-analysis. VO₂peak was significantly lower in CKD patients than controls without CKD [standardized mean difference (SMD) -1.40, 95% confidence interval (CI) -1.68; -1.13)]. Values were lower for CKD than non-CKD individuals for oxygen consumption at anaerobic threshold (SMD -1.06, 95% CI -1.34; -0.79) and maximum workload [weighted mean difference (WMD) -58.26, 95% CI 74.14; -42.38]. In 3 studies, CKD patients had higher VO₂peak than controls with heart failure without CKD (WMD 6.60, 95% CI 3.02; 10.18). Sensitivity analyses confirmed the robustness of these findings.

CONCLUSIONS

VO₂peak and other commonly analyzed CPET variables were lower in patients with CKD than controls, which indicates reduced functional cardiopulmonary reserve in CKD. In contrast, patients with CKD performed better than controls with heart failure without CKD. Overall, rehabilitation programs should be more widely applied to individuals with CKD.

PROSPERO REGISTRATION NUMBER

CRD42021227805.

Cardiac and Noncardiac Determinants of Exercise Capacity in CKD

BACKGROUND

Impaired exercise capacity is a significant symptom of CKD and is associated with poor survival. Furthermore, there is a growing interest in applying exercise as a diagnostic tool or as therapy in CKD. However, an in-depth understanding of exercise physiology in CKD is still lacking.

METHODS

To evaluate the role of cardiac (central) and noncardiac (peripheral) determinants of exercise capacity in CKD, we conducted a cross-sectional study of 70 male patients with CKD (stages 2-5) without diabetes or cardiac disease, 35 healthy controls, and 25 patients with heart failure. An integrated cardiopulmonary exercise test using a CO₂ rebreathing technique was used to measure peak O₂ consumption (VO_2peak) and peak cardiac output simultaneously, and to calculate peak peripheral O₂ extraction (C[a-v]O₂), the peripheral determinant (the ability of exercising skeletal muscles to extract oxygen). We performed multiple regression analysis and used Bayesian information criteria (BIC) changes to quantitatively assess the individual contribution of central and peripheral factors.

RESULTS

Compared with healthy controls, in patients with CKD, the VO_2peak was impaired proportionate to its severity. Peak cardiac output was the predominant determinant of VO_2peak in healthy controls and patients with heart failure, whereas C(a-v)O₂ played a more significant role in determining VO_2peak in CKD (β=0.68, P<0.001) compared with cardiac output (β=0.63, P<0.001). In addition, the magnitude of BIC reduction was greater for C(a-v)O₂ compared with cardiac output (BIC, 298.72 versus 287.68) in CKD.

CONCLUSIONS

In CKD, both peak cardiac output and peak C(a-v)O₂ are independent predictors of VO_2peak, and the more significant roleplayed by peak C(a-v)O₂ highlights the importance of noncardiac factors in determining exercise capacity in CKD.

Assessment of Exercise Intolerance in Patients with Pre-Dialysis CKD with Cardiopulmonary Function Testing: Translation to Everyday Practice

BACKGROUND

Chronic kidney disease (CKD) is often characterized by increased prevalence of cardiovascular risk factors and increased incidence of cardiovascular events and death. Reduced cardiovascular reserve and exercise intolerance are common in patients with CKD and are associated with adverse outcomes.

SUMMARY

The gold standard for identifying exercise limitation is cardiopulmonary exercise testing (CPET). CPET provides an integrative evaluation of cardiovascular, pulmonary, hematopoietic, neuropsychological, and metabolic function during maximal or submaximal exercise. It is useful in clinical setting for differentiation of the causes of exercise intolerance, risk stratification, and assessment of response to relevant treatments. A number of recent studies have used CPET in patients with pre-dialysis CKD, aiming to assess the cardiovascular reserve of these individuals, as well as the effect of interventions such as exercise training programs on their functional capacity. This review provides an in-depth description of CPET methodology and an overview of studies that utilized CPET technology to assess cardiovascular reserve in patients with pre-dialysis CKD. Key Messages: CPET can delineate multisystem changes and offer comprehensive phenotyping of factors determining overall cardiovascular risk. Potential clinical applications of CPET in CKD patients range from objective diagnosis of exercise intolerance to preoperative and long-term risk stratification and providing intermediate endpoints for clinical trials. Future studies should delineate the association of CPET indexes, with cardiovascular and respiratory alterations and hard outcomes in CKD patients, to enhance its diagnostic and prognostic utility in this population.

Efficacy of aerobic exercise on the cardiometabolic and renal outcomes in patients with chronic kidney disease: a systematic review of randomized controlled trials

BACKGROUND

Several randomized controlled trials (RCTs) have demonstrated the cardiometabolic effects of aerobic exercise in the general population and in patients with cardiovascular diseases. However, the efficacy of aerobic exercise in patients with chronic kidney disease (CKD) remains to be elucidated.

METHODS

RCTs comparing aerobic exercise with no aerobic exercise in patients with CKD not requiring kidney replacement therapy were identified through PubMed using RobotAnalyst, a web-based software system that combines text-mining and machine learning algorithms for organizing references. Cardiometabolic and renal outcomes of interest included body mass index (BMI); systolic blood pressure (SBP); hemoglobin A1c (HbA1c), total cholesterol (TCHO), low- and high- density lipoprotein cholesterol (LDLC and HDLC, respectively), and urinary protein (UP) levels/concentration; peak oxygen uptake (Vo₂peak); and glomerular filtration rate (GFR) at the end of the follow-up period. The standardized mean difference (SMD) of each outcome was estimated using the DerSimonian-Laird random-effect model with inverse-variance weighting.

RESULTS

A total of 15 trials, including 622 patients, were included. Their follow-up periods were 3-4, 6-12, and > 12-months in 7 (46.7%), 7 (46.7%), and 1 (6.7%) trial(s), respectively. Meta-analyses showed that aerobic exercise significantly decreased BMI (SMD, -0.19 [95% confidence interval, -0.38, -0.00]) and SBP (-0.75 [-1.24, -0.26]) and increased Vo₂peak (0.54 [0.29, 0.78]); however, no significant association was observed in HbA1c, TCHO, HDLC, LDLC, GFR, and UP. Meta-regression models suggested that aerobic exercise was more likely to improve Vo₂peak in patients with younger age, no diabetes, and lower BMI.

CONCLUSION

Aerobic exercise of 3-12 months' duration improved obesity, high blood pressure, and low exercise capacity in overweight/obese patients with CKD, but it had no significant effect on GFR and proteinuria. Well-designed large RCTs with a longer follow-up period are needed to evaluate the efficacy of aerobic exercise in patients with CKD.

Cardiovascular Functional Changes in Chronic Kidney Disease: Integrative Physiology, Pathophysiology and Applications of Cardiopulmonary Exercise Testing

The development of cardiovascular disease during renal impairment involves striking multi-tiered, multi-dimensional complex alterations encompassing the entire oxygen transport system. Complex interactions between target organ systems involving alterations of the heart, vascular, musculoskeletal and respiratory systems occur in Chronic Kidney Disease (CKD) and collectively contribute to impairment of cardiovascular function. These systemic changes have challenged our diagnostic and therapeutic efforts, particularly given that imaging cardiac structure at rest, rather than ascertainment under the stress of exercise, may not accurately reflect the risk of premature death in CKD. The multi-systemic nature of cardiovascular disease in CKD patients provides strong rationale for an integrated approach to the assessment of cardiovascular alterations in this population. State-of-the-art cardiopulmonary exercise testing (CPET) is a powerful, dynamic technology that enables the global assessment of cardiovascular functional alterations and reflects the integrative exercise response and complex machinery that form the oxygen transport system. CPET provides a wealth of data from a single assessment with mechanistic, physiological and prognostic utility. It is an underutilized technology in the care of patients with kidney disease with the potential to help advance the field of cardio-nephrology. This article reviews the integrative physiology and pathophysiology of cardio-renal impairment, critical new insights derived from CPET technology, and contemporary evidence for potential applications of CPET technology in patients with kidney disease.

Gradual reduction in exercise capacity in chronic kidney disease is associated with systemic oxygen delivery factors

Background

The cause of reduced exercise capacity (ExCap) in chronic kidney disease (CKD) is multifactorial. The aim of this study was to investigate determinants of aerobic ExCap in patients with mild to severe CKD not undergoing dialysis.

Methods

We included 52 individuals with CKD stage 2–3, 47 with stage 4–5, and 54 healthy controls. Peak workload and peak heart rate (HR) were assessed by a maximal cycle exercise test. Cardiac function including stroke volume (SV) and vascular stiffness were evaluated by ultrasound at rest. Handgrip strength, body composition, haemoglobin level and self-reported physical activity were assessed.

Results

Peak workload (221±60, 185±59, 150±54 W for controls, CKD 2–3 and CKD 4–5 respectively), peak HR (177±11, 161±24, 144±31 beats/min) and haemoglobin level (14.2±1.2, 13.5±1.4, 12.2±1.3 g/dL) were all three significantly lower in CKD 2–3 than in controls, (p = 0.001, 0.001 and 0.03 respectively) and were even lower in stages 4–5 CKD than in CKD 2–3 (p = 0.01, 0.001 and <0.001 respectively). Resting SV and lean body mass did not differ between groups and handgrip strength was significantly lower only in CKD 4–5 compared to controls (p = 0.02). Peak workload was strongly associated with the systemic oxygen delivery factors: SV, peak HR and haemoglobin level. These three factors along with age, sex and height² explained 82% of variation in peak workload. Peak HR contributed most to the variation; the peripheral variables handgrip strength and vascular stiffness did not improve the explanatory value in regression analysis.

Conclusions

In this cross-sectional study of CKD patients not on dialysis, aerobic ExCap decreased gradually with disease severity. ExCap was associated mainly with systemic oxygen delivery factors, in particular peak HR. Neither muscle function and mass, nor vascular stiffness were independent determinants of aerobic ExCap in this group of CKD patients.

Identifying early decline of daily function and its association with physical function in chronic kidney disease: performance-based and self-reported measures

Objective

To verify self-reported basic and instrumental activities of daily living (IADL) with a disability and the results of performance-based tests (namely the Taiwan performance-based IADL (TPIADL), the 2-minute step test (2MST), the 30-second chair-stand test (30-s CST), and handgrip dynamometer measurement) to identify disability early and assess the associations with functional fitness in patients with advanced chronic kidney disease (CKD).

Methods

A cross-sectional study of 99 patients with stage 4-5 CKD and 57 healthy elderly adults were recruited. Self-reported measures were used to collect information on basic (Barthel Index) and IADL (Lawton-Brody scale). Objective measures of the TPIADL and functional fitness (2MST, 30-s CST, handgrip dynamometer) were also assessed.

Results

Only IADL, as detected by the TPIADL, were impaired to a greater extent in the CKD patients than those of healthy elderly adults. Among all the patients with CKD, a greater impairment in the TPIADL remained statistically associated with a lower ability in the 2MST. A one step increase in the 2MST score was significantly associated with an improvement of 0.2 s in the total performance time of the TPIADL.

Conclusion

Performance-based measures, such as the TPIADL, may detect a functional limitation before it becomes measurable by traditional self-reported basic and IADL scales; functional limitation is mainly associated with cardiac endurance for advanced CKD.

Cardiopulmonary exercise testing reveals subclinical abnormalities in chronic kidney disease

Background

Reductions in exercise capacity associated with exercise intolerance augment cardiovascular disease risk and predict mortality in chronic kidney disease. This study utilized cardiopulmonary exercise testing to (a) investigate mechanisms of exercise intolerance; (b) unmask subclinical abnormalities that may precede cardiovascular disease in chronic kidney disease.

Design

The design of this study was cross-sectional.

Methods

Cardiopulmonary exercise testing was carried out in 31 Stage 3–4 chronic kidney disease patients (60 ± 11 years; estimated glomerular filtration rate 43 ± 13 ml/min/1.73 m2) and 21 matched healthy individuals (healthy controls; 56 ± 5 years; estimated glomerular filtration rate>90 ml/min/1.73 m2) on a cycle ergometer with workload increased by 15 W every minute until volitional fatigue. Breath-by-breath respiratory gas analysis was performed with an automated gas analyzer and averaged over 10 s intervals.

Results

Peak oxygen uptake was reduced in chronic kidney disease compared to healthy controls (17.43 ± 1.03 vs 28 ± 2.05 ml/kg/min; p < 0.01), as was oxygen uptake at the ventilatory threshold (9.44 ± 0.53 vs15.55 ± 1.34 ml/kg/min; p < 0.01). A steeper minute ventilation rate/carbon dioxide production slope (32 ± 0.8 vs 28 ± 1; p < 0.01) and a lower expired carbon dioxide pressure in chronic kidney disease (27 ± 0.6 vs 31 ± 0.9 vs 0.9; p < 0.01) indicated ventilation perfusion mismatching in these patients. The ventilatory cost of oxygen uptake was higher in chronic kidney disease (37 ± 0.8 vs 33 ± 1; p < 0.01). Maximum heart rate (134 ± 5 vs 159 ± 3 bpm) and one-minute heart rate recovery (15 ± 1 vs 20 ± 2 bpm) were reduced in chronic kidney disease ( p < 0.01).

Conclusion

This study suggests that both central and peripheral limitations likely contribute to reduced exercise capacity in non-dialysis chronic kidney disease. Additionally, cardiopulmonary exercise testing revealed subclinical cardiopulmonary abnormalities in these patients in the absence of overt cardiovascular disease. Cardiopulmonary exercise testing could potentially be a tool for unmasking cardiopulmonary abnormalities preceding cardiovascular disease in chronic kidney disease.

Effect of aqueous extract and anthocyanins of calyces of Hibiscus sabdariffa (Malvaceae) in rats with adenine-induced chronic kidney disease

OBJECTIVES

The aim of this work was to assess the possible beneficial effects of aqueous extracts of Hibiscus sabdariffa L. calyces and anthocyanins isolated therefrom in an adenine-induced chronic kidney disease (CKD) model.

METHODS

Rats were orally given, for 28 consecutive days, either adenine alone or together with either aqueous extract of H. sabdariffa calyces (5 and 10%) or anthocyanins (50, 100 and 200 mg/kg of anthocyanin concentrate). For comparative purposes, two groups of rats were given lisinopril (10 mg/kg).

KEY FINDINGS

When either H. sabdariffa aqueous extract or the anthocyanins isolated from it was administered along with adenine, the adverse effects of adenine-induced CKD were significantly lessened, mostly in a dose-dependent manner. The positive effects were similar to those obtained by administration of lisinopril.

CONCLUSIONS

The results obtained show that both H. sabdariffa and its anthocyanins could be considered as possible promising safe dietary agents that could be used to attenuate the progression of human CKD. This could have added significance as H. sabdariffa tea is widely consumed in many parts of Africa and Asia and is thus readily available.

The effect of swimming exercise on adenine-induced kidney disease in rats, and the influence of curcumin or lisinopril thereon

Patients with chronic kidney disease (CKD) have been reported to benefit from different types of exercises. It has also been shown that the ACE inhibitor lisinopril, and the natural product curcumin are also beneficial in different models of CKD in rats. We assessed the influence of moderate swimming exercise (SE) on rats with adenine-induced CKD, and tested the possible effects of lisinopril and/or curcumin thereon using several physiological, biochemical, histopathological and immunohistochemical parameters. Rats (either sedentary or subjected to SE) were randomly divided into several groups, and given for five weeks either normal food or food mixed with adenine (0.25% w/w) to induce CKD. Some of these groups were also concomitantly treated orally with curcumin (75 mg/kg), or lisinopril (10 mg/kg) and were subjected to moderate SE (45 min/day three days each week). Rats fed adenine showed the typical biochemical, histopathological signs of CKD such as elevations in blood pressure, urinary albumin / creatinine ratio, and plasma urea, creatinine, indoxyl sulfate and phosphorus. SE, curcumin or lisinopril, given singly, significantly ameliorated all the adenine-induced actions. Administering curcumin or lisinopril with SE improved the histopathology of the kidneys, a salutary effect not seen with SE alone. Combining SE to the nephroprotective agents' curcumin or lisinopril might offer additional nephroprotection.